Flame Retardant Acrylonitrile Copolymer via Segmented Prepolymerization
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Solution Overview
Problem
Acrylonitrile-based copolymers used in textile production lack sufficient flame retardance, and existing methods to enhance this property, such as adding halogen-containing monomers, complicate copolymerization and reduce polymerization degree.
Innovation Solution
A method involving the prepolymerization of two compositions, each containing acrylonitrile and a halogen-containing vinyl monomer like vinylidene chloride, with specific weight ratios and molecular weights, followed by mixing and polymerization to produce a flame retardant modified acrylonitrile-based copolymer with improved molecular weight and flame retardance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a halogen-containing monomer (vinylidene chloride) is added to the reaction system to improve flame retardance, then the flame retardance of the copolymer is improved, but the copolymerization reaction becomes complicated and the polymerization degree is considerably reduced
Solution Approach 1:
The patent divides the copolymerization process into two separate stages: first polymerizing acrylonitrile with a small amount of vinylidene chloride to obtain a prepolymer, then using this prepolymer as a copolymerizing agent in a second polymerization with acrylonitrile and additional vinylidene chloride. This segmentation simplifies each individual polymerization step while achieving the desired flame retardant properties in the final product.
Solution Approach 2:
The patent performs preliminary polymerization to create a prepolymer containing acrylonitrile and vinylidene chloride before the main copolymerization step. This preliminary action prepares a controlled intermediate product that facilitates the subsequent copolymerization reaction, reducing complexity and improving polymerization degree.
2Reliability
If a halogen-containing monomer (vinylidene chloride) is added to the reaction system to improve flame retardance, then the flame retardance of the copolymer is improved, but the polymerization degree is considerably reduced
Solution Approach 1:
The patent segments the polymerization into two stages: first creating a prepolymer with controlled vinylidene chloride content (1-10 wt%), then using this prepolymer in a second polymerization with acrylonitrile and additional vinylidene chloride (20-50 wt%). This segmentation maintains high polymerization degree by controlling monomer concentrations in each step while achieving the required flame retardance in the final product.
Solution Approach 2:
The preliminary polymerization step creates a prepolymer with specific composition and molecular weight characteristics that serve as optimal starting material for the main copolymerization. This preliminary action ensures that the final product achieves both high polymerization degree and sufficient flame retardance properties.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method achieves a high degree of copolymerization, resulting in a flame retardant acrylonitrile-based copolymer with enhanced flame retardance, as indicated by a limiting oxygen index greater than 27%, while maintaining excellent chemical and physical properties.
Implementation Method 1
polymerizing a first composition to obtain a first copolymer solution including a first copolymer; polymerizing a second composition to obtain a second copolymer solution including a second copolymer
Data Source
AI summary
A method for preparing a flame retardant modified acrylonitrile-based copolymer, includes: prepolymerizing a first composition to obtain a first prepolymer solution including a first prepolymer; prepolymerizing a second composition to obtain a second prepolymer solution including a second prepolymer; and mixing the first and second prepolymer solutions and subjecting a mixture of the first and second prepolymers to polymerization to obtain a flame retardant modified acrylonitrile-based copolymer solution containing a flame retardant modified acrylonitrile-based copolymer.